Sorry, I think it is a conversion issue because I have noticed some unusual zeroes in the dihedral force constants in the amber .prmtop file.
Thank you,

Hi, I created the 'ParmEd structure' instance from 'openMM system' and after that, I saved the amber parameter file and coordinate file from the ParmEd structure because I want to use Amber. But when I am calculating the system's potential energy in Amber, I am getting it different from what I got u...